Spring-Over Axle lift on an early model Isuzu.
Short Cuts
Authoring and Photography By:Dan Houlton
First Published: April 2000

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Reducing the lift
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Look closely at the leaves. You can see the bend in the main leaf.

As mentioned before, the SOA lift by itself will give about 6" of lift which is likely quite a bit more than you want since the maximum you can lift the front is about 3". I did a couple things to reduce this lift. One was to cut off the hangers for the front of the springs and make some new ones, and the other was to remove the middle spring from the spring pack. I wouldn't suggest the latter though. Removing the middle spring took out about an inch of the lift, but it also left the main leaf unsupported for a good portion of it's length. On my first trip out, I put a nice reverse bend in the main leaf right right at the end of the short leaf. It actually turned out ok though as the bends on both sides were about the same, and after putting the middle leaves back in, I still had lost an inch of lift from the bent main leaves.

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The new spring hangers (top) tuck the spring up about 2" higher than stock (above).

If you have a torch and welder, you can cut off the old hangers and mount some new ones. The stock hangers drop down below the frame rail several inches. With new hangers, you can gain more ground clearance over the stock hangers, and also mount the front of the spring just shy of 2" higher. This works in reverse of what extend shackles do and ends up removing about an inch from the ride height.

The hanger you see here are some I made up, but I think they're a bit over done. The idea was to keep the bottom of the hanger more or less flush with the bottom of the frame rail and make a smooth ramp so that if you were sitting it on a rock, it would slide along it easier. Hopefully, the back end would lift up onto said rock before your springs started dragging against it though. I also wanted a large hanger as I was concerned with welding to the frame. A large hanger meant I have a lot more area I can weld to the frame on and spread the load out. I've seen much simpler designs used though that are nothing more than a piece of tubing welded and gusseted to a flat piece of steel which is then welded to the bottom of the rail. I wasn't sure of the strength (especially laterally) of such a design when I did this, but since then have seen it used in several places so it must be ok.

So, what to do if you don't have a torch and welder? Even if you do, I must admit, I found it very hard (mentally anyways) to start cutting things off the frame. If you want to avoid this level of work, probably the easiest method is to remove the bottom overload leaf. This is the thick bottom leaf in the pack. Removing it will remove about 5/8" just because of it's thickness, but it'll also let the rest of the pack flatten out much more. How much I can't say, but it's likely be close enough to not have to do additional work  If it's too much, just flip it over instead of removing it. That'll let the spring pack flatten out more, but not as much as removing it and you still have the thickness of it in the pack.

If you do remove the overload leaf, understand that you also loose a portion of your load carrying ability. If you load up a lot of weight, the springs will really sag without the support of the overload leaf. I know one person that countered this by using an air bag spring. It's mounted over the differential in back so that it gives support and extra load carrying ability when needed, but it won't interfere with axle articulation on the trail.

You might find too, that if you have an older vehicle, then the springs have sagged quite a bit from age. I know one person that had this situation. That, combined with the fact that he routinely carried several hundred pounds of parts and tools in back let him do the SOA conversion without having to reduce the lift. His saggy springs and the weight he carried meant his back end was already lower than the front when stock and the extra lift of the SOA conversion tended lift the back slightly higher than the front again.

Another option to look at is to have your springs de-arched slightly. Again, if your springs are old and sagging already, this is probably not needed. If you flip the overload leafs though and still can't get enough lift out and don't want to remove it entirely, then de-arching the springs is an option. De-arching does just that to the springs. It removes some of the arch to make them flatten out more. Be very careful if you have this done as you don't want it de-arched too much.

The Drive Shaft

The final issue is your drive shaft length. Depending on your particular truck, you may need to have the drive shaft lengthened. There were different kinds depending on year and model. The earlier year Amigo's used a plunging shaft into the back of the transfer case, the later years used a flange on the output shaft of the transfer case just like the one that's on the pinion, and the drive shaft had a slip joint in it. The longer Trooper and Rodeo use a two piece drive shaft with a carrier bearing towards the middle.

I have the type with two flanges and a slip joint in the shaft. I found that I could still use the stock shaft, but I had in-advertently moved the rear axle forward slightly when I welded the new spring hangers in place. I have since moved the axle back to a little bit rearward of where it was stock and I did have the drive shaft re-tubed. I could probably have gotten away with the stock drive shaft, but the slip joint was extended compared to it's stock position and I didn't want to risk pulling it apart or twisting the splines due to a small engagement area. I can't remember now how much it was lengthened, but I think it was around 2". The cost at a local shop to do it was around $80.

Your best bet is to mark the slip joint on whatever type of drive shaft you have before doing the lift. Then put it back in after the lift and see how much further the joint has extended. Then lift the back so the axle is off the ground and measure again. If you decide it's extended too much, you'll know exactly how much you'll need to add to the length. You may also decide it's not enough to worry about.

Final Notes

Good luck with your conversion. With a little time and patients, you can end up with a nicely lifted rig that'll still give a decent ride and excellent flex on the trail. Don't be afraid to ask questions either. Use the Isuzu Discussion Board to look for advice. Myself and some others that have done this conversion watch the board continually and we'll be glad to help any way we can.

Contacts & Related Information:

  • AFCO Racing
    977 Hyrock Blvd
    Boonville, IN 47601 U.S.A.
    Phone 1-812-897-0900
    Fax 1-812-897-1757
    Racing and Suspension Specialist

  • Lou Fergers Racing Equipment
    512 E. Hwy. 12
    Delano, MN 55328 U.S.A.
    Phone 1-800-328-3618
    Fax 1-612-972-6658
    Racing Equipment Supplier

  • Earl's Perfomance Products
    15827 Hawthorne Blvd
    Lawndale, CA 90260 U.S.A.
    Phone 1-323-772-3605
    Order Line 1-310-644-0881 (U.S.A.)
    High-Performance Plumbing